Fast: Twig compiles templates down to plain optimized PHP code. The overhead compared to regular PHP code was reduced to the very minimum.

Secure: Twig has a sandbox mode to evaluate untrusted template code. This allows Twig to be used as a template language for applications where users may modify the template design.

Flexible: Twig is powered by a flexible lexer and parser. This allows the developer to define its own custom tags and filters, and create its own DSL.

Extensibility: Twig is flexible enough for all your needs, even the most complex ones. Thanks to an open architecture, you can implement your own language constructs (tags, filters, functions, and even operators) to create your very own DSL.

Unit tested: Twig is fully unit-tested. The library is stable and ready to be used in large projects.

Documented: Twig is fully documented, with a dedicated online book, and of course a full API documentation.

Secure: When it comes to security, Twig has some unique features:

Automatic output escaping: To be on the safe side, you can enable automatic output escaping globally or for a block of code.

Sandboxing: Twig can evaluate any template in a sandbox environment where the user has access to a limited set of tags, filters, and object methods defined by the developer. Sandboxing can be enabled globally or locally for just some templates.

Clean Error Messages: Whenever you have a syntax problem within a template, Twig outputs a helpful message with the filename and the line number where the problem occurred. It eases the debugging a lot.

Fast: One of the goals of Twig is to be as fast as possible. To achieve the best speed possible, Twig compiles templates down to plain optimized PHP code. The overhead compared to regular PHP code was reduced to the very minimum.